The present invention concerns a method to protect integrated circuits by providing circuitry which isolates a pin when bus contention is detected.
Circuit boards often contain a number of integrated circuits. During testing of a circuit board, typically the circuit board is powered up and a tester places test vectors on the inputs of one or more integrated circuits. However the placement of test vectors on some integrated circuits can result in the tester overdriving the outputs of other integrated circuits which are on the board and which are not being tested. When the output of an integrated circuit is overdriven for an extended period of time, the current generated can cause metal migration and other destructive defects within the integrated circuit.
It is desirable, therefore, to stop the tester induced failures and long term reliability problems which can occur when a tester overdrives output pins of integrated circuits.